A raster-type plotter apparatus has heretofore been known which performs a printing with a full bit-map system for converting one page (or plural pages) of whole input image data into raster data so as to develop the converted data in a memory.
This full bit-map system needs a large storage capacity of the memory because it must develop one page (or plural pages) of raster data in the memory. Specifically, a raster-type plotter apparatus employing 128 heads with nozzles of 360 dpi (the number of dots per inch (25.4 mm)) capable of plotting A0 size (W.times.L: 841 mm.times.1,189 mm), needs to have 186 (Kbytes).times.1189 (mm)/25.4 (mm).div.128/360=about 24 Mbytes of the storage capacity of the memory for developing therein one page of input image data into raster data. The "186 (Kbytes)" is a necessary storage capacity for the memory to develop, therein, one band portion of the input image data into the raster data.
In such raster plotter apparatuses with the full bit-map system, the need of the large storage capacity for the memory has increased the cost of the plotter apparatus.
On the other hand, raster-type plotter apparatuses employing a banding processing have also been known. The banding processing is mainly used for such plotter apparatuses as having a moving carriage on which recording heads are mounted, wherein the input image data are converted into intermediate codes per region of a determined unit (for example per band) and the converted intermediate codes are then converted into the raster data. Here, the "band" is referred to as a strip region which is recorded in one scanning of the heads.
In order to produce data of one vector, it is necessary to define two end points (head and tail end points) of the vector as well as modifying information of the vector (i.e., plotter parameters) including line length, line width, shape of the line ends, and the like, as shown in FIG. 8. Thus, the raster-type plotter apparatus using the banding processing, first, converts the raster data, which are defined by the head and tail end points as shown in FIG. 9, with various modifying information added, into the intermediate codes of a so-called display list and, then, performs a vector-to-raster conversion (VRC) with respect to the intermediate codes. The intermediate codes are data of a format which is adapted for use in the vector-to-raster conversion, and comprises coordinate data, which constitute respective contours of the vectors, on which the modifying information has been reflected, band by band, based on the vector data of the input image data. Incidentally, the intermediate codes will be described below more in detail.
Thus, by converting the intermediate codes, which are produced prior to the printing, into the raster data in a band-by-band manner, it is possible to avoid the inconvenience of developing the incoming image data as a whole in a memory as in the full bit-map raster-type plotter apparatus mentioned above, to thereby reduce the necessary capacity of the memory.
More specifically, in a raster-type plotter apparatus employing 128 heads with nozzles of 360 dpi capable of plotting A0 size, the necessary storage capacity of the memory for developing one band portion of the input image data into the raster data is: EQU 841 (mm)/25.4 (mm).times.360 (dpi).times.128=about 186 KBytes
the capacity of the storage is drastically reduced as compared to that of aforementioned raster-type plotter apparatus employing the full bit-map system.
Such a raster-type plotter apparatus employing the banding processing is supposed to use the intermediate codes when re-plotting the data which were plotted previously, and such intermediate codes have been produced in the form of coordinate data on which the modifying information has been reflected. For this reason, it is difficult to perform, afterward, additional processing such as rotation, enlargement, reduction, and change of line width.
Incidentally, it is possible to re-produce the intermediate codes, after changing respective plotting parameters, with respect to partial input image data for each band, by increasing the capacity of an input buffer memory, which temporarily stores the input image data, so as to utilize the data stored in the input buffer memory. However, in order to accomplish this, the input buffer memory needs a large storage capacity, suffering from problems in mounting parts and in cost of the raster-type plotter apparatus, and hence this approach is not practical.
Further, another prior art apparatus has been known which includes means for relocate images for elimination of wasting papers when a plurality of separate images are recorded on the same paper. Instead of placing plural images vertically along a long paper sheet in the order of receiving the images as shown in FIG. 19(a), the image relocation means relocates the images as shown in FIG. 19(b). Conventionally, such relocation of the images is performed, when converting the input image data into the intermediate codes, by determining the positions of the relocation, taking into consideration the sizes of the respective images of the input image data, which are to be formed on an actual paper sheet.
However, this approach requires that the size of the actual paper sheet and the sizes of respective images should be settled prior to the conversion of the input image data into the intermediate codes. For this reason, the size of the actual paper sheet must be known based on a user's instruction or information given from a print engine 26. Also, regarding the image size, it is required that each image size should explicitly be specified in the form of a data header or the like, or a user's explicit instruction, prior to the initiation of the image data input. Therefore, if, during plot of an image, next image data are inputted for which the size of a paper sheet to be supplied is unsettled, the intermediate codes for the input image data are not produced, making an idle time in a CPU operation, which causes a problem in efficiently using the CPU.
In view of the foregoing problems, an object of the present invention is to provide an image processor which converts input image data into raster data without having a memory of a large storage capacity for bit-map development and makes it possible to change modifying information prior to the plotting without having an input buffer memory of a large storage capacity.
Another object of the present invention is to provide an image processor which effectively uses a CPU which can analyze input image data even when the size of a paper sheet for plotting is not settled in advance.